After some thinking I came to a verdict. According to my experience the "Reputation Power" mechanism can have some practical use only at much more populated forums than MasterRussian (with a good statistics). What can be useful at masterrussian is a mechanism of approving posts rather than users. It is like two intuitive pictures like "thumb up" and "thumb down" with "I like this post" and "I dislike this post" balloon hints plus intelligible "This post is approved X times and disapproved Y times" line which can be understood even by a newbie or occasional reader.

Reputation power of the user can go as a sum of all his posts RP as a bonus .

The problem is that good comments often goes along with some muddled and plainly wrong replies. Sometimes I have nothing to add to replies but I want to agree to one post and disagree to another and not to make flood of comments.